This study deals with a computer system for measuring flow rate of tap water flowing in a rigid pipeline in a non-contact method by using an acoustic emission (AE) sensor placed on a surface of a pipeline. The acoustic emission generated by tap water flowing at a constant flow rate in a pipeline is caught by the AE sensor experimentally, and the corresponding output of the AE sensor is converted to a root mean square (RMS) value. It became clear that the relation between flow rate and the

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... ponding RMS value can be expressed as a quadratic curve with good approximation. This quadratic curve is used as the calibration date for measurement of flow rate. A prototype of a flow rate measuring system based on a computer was constructed by taking account of the calibration data. It is shown in the experiment that the flow rate more than 3.21/min can be measured by using the measuring system proposed in this study.